#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

 int print(int n)
{

	if (n <= 2)
		return 1;
	else return print(n - 1) + print(n - 2);
}
int main()
{
	int n = 0;
	scanf("%d",&n);
		int m = print(n);
		printf("%d", m);
	return 0;
}